Regular Article

Influence of Nb₂O₅ and basicity on the viscosity and structure of CaO-SiO₂-Nb₂O₅-CeO₂-CaF₂ slag system

¹ Key Laboratory of Integrated Exploitation of Bayan Obo Multi-Metal Resources, Inner Mongolia University of Science and Technology, Baotou 014010, Inner Mongolia, PR China
² School of Materials and Metallurgy, Inner Mongolia University of Science and Technology, Baotou 014010, Inner Mongolia, PR China
³ Inner Mongolia Autonomous Regional Engineering Technology Research Center of Sustainable Exploitation of Rare Earth Secondary Resources, Inner Mongolia University of Science and Technology, Baotou 014010, Inner Mongolia, PR China

^* e-mail: zhzengwu@imust.cn

Received: 16 January 2020
Accepted: 16 April 2020

Abstract

In order to utilize niobium concentrate of Bayan Obo effectively, the effect of Nb₂O₅ and basicity on the viscosity of CaO-SiO₂-Nb₂O₅-5.0 wt.% CeO₂-5.0 wt.% CaF₂ slag system was studied from 1653 to 1813 K in reducing atmosphere by rotating cylinder method. For the same condition, the as-quenched samples were investigated through X-ray diffraction and Raman spectroscopy. The results show that the viscosity, break temperature and activation energy of viscous flow decrease with the increase of Nb₂O₅ and basicity. Raman spectra show that the Nb⁴⁺ ions exist in the form of [NbO₆] octahedron with different distortion and little [NbO₄] tetrahedron in the slags. The Nb₂O₅ addition and basicity lower the degree of polymerization, where the complex Si-O network is depolymerized into simple structural units.